High pressure presses have been used for decades in the manufacture of, for example, synthetic diamond. Such presses are capable of exerting a high pressure and high temperature on a volume of carbonaceous material to reproduce the conditions that create natural diamond inside the earth. Known designs for high pressure presses include, but are not limited to, belt presses, tetrahedral presses, and cubic presses.
FIG. 1 shows a basic design for a conventional cubic press 10 known in the art. The design generally includes six press bases 12, with each press base 12 aligned relative to a common central region 14. Each press base 12 exhibits a generally tapered geometry, having a first face 18 with one cross-sectional area and a second, opposing face 16 exhibiting a cross-sectional area larger than that of the first face 18.
As shown in FIGS. 2 and 3, a piston cavity 20 is formed in the first face or surface 18 of each press base 12 and a piston 22 is disposed therein. Piston 22 may be thrust out of piston cavity 20 and towards common central region 14 shown in FIG. 1 by, for example, the introduction of hydraulic fluid into piston cavity 20. In operation, pistons 22 are displaced out of their associated press bases 12 towards common central region 14 to exert pressure on each face of a cubic volume of carbonaceous material located at common central region 14.
Piston cavity 20 exhibits a generally cylindrical shape and includes a side wall 21 that is generally perpendicular to a bottom 23 of piston cavity 20. Piston cavity 20 also has a small radius 25 providing a curved transition at the juncture of side wall 21 and bottom 23 of piston cavity 20.
Piston 22 is received in piston cavity 20 and has a size and shape approximately equal to the size and shape of piston cavity 20, including a radiused or chamfered edge 27 at a bottom corner of piston 22 to allow clearance of radius 25 in piston cavity 20. Press base 12 includes a fluid input line 24 which extends from an outer side surface 28 of press base 12 to bottom 23 of piston cavity 20. Hydraulic fluid is pumped into piston cavity 20 via fluid input line 24, which then causes piston 22 to be displaced out of piston cavity 20 with a desired amount of force.
As piston 22 is displaced towards common central region 14 and applies pressure to a cubic volume located at common central region 14, counter forces act on piston 22. Counter forces may result from the resistance by the cubic volume as well as the other pistons 22 pushing against the cubic volume from other directions. Ideally, the counter forces are cumulatively balanced. In other words, it is preferable that the magnitude and direction of the forces are such that they counteract one another and focus the force on the central region. Under such conditions, any stress or strain experienced by the components of the cubic press is within predicted design parameters.
However, ideal operation of the cubic press is difficult to achieve due to the many factors. Indeed, some imbalance is typically exhibited between the forces and counter forces distributed among the press bases 12. For example, misaligned components of the cubic press 10 may lead to uneven and misdirected forces and counter forces. Imperfections in the manufacture of components, such as surface imperfections, may also lead to uneven and misdirected counter forces. Additionally, imbalanced hydraulics, whether due to the design of the hydraulics system, improper functioning of hydraulic components, or other inherencies within the system, may result in imbalanced forces within a given press.
Thus, referring to FIG. 4, the desired direction of a counter force is along the same axis A that piston 22 moves along as it is displaced out of piston cavity 20. However, FIG. 4 also illustrates how factors as described above may result in counter forces that combine to act along a different axis B, which is different than the axis along which the pistons are thrust out of the piston cavities.
Uneven and misdirected counter forces may result in detrimental stresses being applied to the components of cubic press 10, including press bases 12. When too much stress is exerted on these components, cracks may begin to form. Once cracks are formed, press bases 12 are weakened and further deformation, crack propagation and component failure become more likely. In other words, cracking and undue bending of components of cubic press 10 can lead to a shorter fatigue life for such components and, thus, more failures of the device, more maintenance and higher operating costs.
Thus, it would be advantageous to provide an improved press base of a high pressure press, improved components for a press base as well as methods of improving a press base of a high pressure press.